Science might be able to explain our fascination with Brad Pitt's chiseled jaw and George Clooney's smoldering eyes.

Women seem to judge potential mates by how masculine their features are, new research shows. Men with square jaws and well-defined brow ridges are seen as good short-term partners, while those with more feminine traits such as a rounder face and fuller lips are perceived as better long-term mates.

In the study, 854 male and female subjects viewed a series of male head shots that had been digitally altered to exaggerate or minimize masculine traits. The participants then answered questions about how they expected the men in the photos to behave.

Overwhelmingly, participants said those with more masculine features were likely to be risky and competitive and also more apt to fight, challenge bosses, cheat on spouses and put less effort into parenting. Those with more feminine faces were seen as good parents and husbands, hard workers and emotionally supportive mates [compare examples].

Despite all the negative attributes, when asked who they would choose for a short-term relationship, women still selected the more masculine looking men. Brad and George then would be picks for a brief romance, if not the long haul."